I think that your fundamental question is interesting but extremely vague. I understand your question about authenticity to involve relevance. Because what lies at the heart of your questions is the possible meaning of what one understands by the word “authentic”. Authenticity was a buzz word for Martin Heidegger, and the Frankfurt School writers really took him to task over it. The whole question of authenticity in art and cultural production is now permanently coloured by that set of considerations and the ensuing debate.
Hence, I prefer to think of your question in non-absolute terms and use relevance as a yard-stick. If the work is relevant to its historical moment then it is authentic, either on a personal or public level. I would make a distinction between historical moment and fashionable interest, unless that fashionable interest was of a critical nature. The question of fashionable awareness and critical or historical awareness is not essential to art production, but does make a difference to the importance of the artwork to the viewer in terms of its relevance. In other words, the issue of the the work being simply a matter of entertainment, craft, or diversion rather than of critical intellectual engagement stems from its perceived relevance to the viewer and that viewer’s circumstances. Any perception of relevance that the work has is inherent in the context for the work that is provided by the viewer, that is, how the interpreter of the artwork (as a sign) constructs the relevance of the sign that is under consideration. This understanding follows on from C.S. Peirce’s definition of a sign being that which means something to someone. The issue of essentialism is another whole discussion that is very fraught.
– John Penny